<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"
        "http://www.w3.org/TR/html4/loose.dtd">
<html>
    <head>
        <title>Class selector</title>
        <style type="text/css">
            p {
                color: green;
            }

            /* red is a class */
            /* Apply for only p and h2 with red class */
            p.red, h2.red {
                color: red;
            }

            /* Apply for all element with red class */
            .red {
                color: red;
            }
        </style>
    </head>
    <body>
        <p>Android Studio provides the fastest tools for building apps on every type of <em>Android</em> device.</p>
        <p class="red">Android Studio provides the fastest tools for building apps on every type of <em>Android</em> device.</p>

        <h1 class="red"> h1 </h1>
        <h2> h2 </h2>
        <h2 class="red"> h2 </h2>
    </body>
</html>